Arctic Cloud Microphysical Characteristics from 8-year Space-based lidar CALIOP Measurements

An accuate determination of cloud amount, height and associated optical porperites is critical to studying the Arctic climate system and its changes. Arctic clouds are a key factor in determining the energy budget both at the top of the atmosphere and at the suface by modulating the long-wave and short-wave radiative fluxes, which affect the surface temperature and may effect on the growth or retreat of sea ice extent and thickness. In this work, we exmine three-dimensional geometric and microphysical properties of Arctic clouds mainly from eight-year space-borne lidar Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) onboard Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO). CALIOP utilizes the return signal from light pulses to identify cloud height and asscociated optical and microphysical properties, and is generally known to perform well even on cloud and highly reflective surfaces. Cloud coverages from CALIOP and MODIS show similar seasonal and inter-annual variations, but shows significant different over the opened sea area (i.e., Barents and Kara Sea) and over the sea ice. High occurrences of cloud top height are found below 2 km. But comparably hign presences of mid- and high-level clouds are also found, especially in winter-time. This suggests that both low- and high-level clouds over the Arctic may influence on the long-wave radiation budget both at the surface and top of the atmosphere, with low-latitude clouds. On the other hand, the top height of winter-time clouds looks consistent with tropopause height. Detailed investigations on the vertical distribution of Arctic clouds (i.e., cloud top and bottom height, cloud thickness, etc.) and cloud droplet type (i.e., ice or water droplet) and microphysical properties (e.g., effective cloud droplet size) and their seasonal and inter-annual characteristics also will be presented.